May-van Deemter model

Van Swaay and Zuiderweg [23] extensively tested the May-van Deemter model as to its ability to scale up the Shell chlorine process (air oxidation of HCl into CI2). To do so they investigated the decomposition of ozone on an FejOs catalyst deposited on sand or silica and carried out gas pulse tracer tests. The bed diameter ranged from 10 to 60 cm, the bed heights from SO to 300 cm. The authors concluded that the van Deemter model adequately describes fluidized bed reactor performance for first-order reactions with a rate coefficient smaller than 2.5 m /kg cat.hr or 1 s" . It follows from their work that with the silica-based catalyst u kj linearly increases from 0.25 m to 0.4 m as u, varies from 6 to 20 cm/s. For fluid beds with a height of up to 1 m, ujkj is proportional to the bed height so that... 

Fig. 14. Conversion for a first order reaction with the May-Van Deemter model (fig. 4).

The approximate additivity of the effects of axial dispersion and mass transfer resistance was first deduced by van Deemter et al. by considering the asymptotic form of model lb. The same conclusion may be reached in a simpler way from- moments analysis and leads to Eq. (8.42) as the definition for an overall effective rate coefficient incorporating both the effects of axial dispersion and finite mass transfer resistance. 

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